add bitcoind to devshell, and setenv BITCOIND_EXE

[nothingmuch]

This change supplies bitcoind from nixpkgs, and sets BITCOIND_EXE to its full path, for more convenient testing.

BITCOIND_SKIP_DOWNLOAD is also set, although that's only actually required in sandboxed builds.

Note that this decouples the bitcoind version from that set in the feature flags of the bitcoind crate, with the default version from nixpkgs being selected and locked in the flake.lock file. I haven't had any problems with it, and ideally tests should pass with all versions.

Also fixes formatting with nix fmt, which I forgot in the cargo-llvm-cov PR.

[coveralls]

Pull Request Test Coverage Report for Build 13000966288

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 78.485%

---

Files with Coverage Reduction	New Missed Lines	%
payjoin/src/send/mod.rs	2	93.79%

Totals
Change from base Build 12968704432:	-0.04%
Covered Lines:	3648
Relevant Lines:	4648

---

💛 - Coveralls

[nothingmuch]

BTW another thing I often do for local development, although not really the topic of this PR I thought I'd mention it here, is nest another nix shell nixpkgs#sccache and set RUSTC_WRAPPER=sccache. If others use the dev shell stuff please lmk your thoughts about that, IME it's a bit slower for some things esp. failed builds, but seems very effective when doing things like git rebase --exec ./contrib/test_local.sh repeatedly, but I did not actually measure this stuff it's just vibes for now.

[DanGould]

If I'm in this nix develop shell is this supposed to supply bitcoind for tests by default? I'm getting this error for every integration test that requires bitcoind when I run ./contrib/test_local.sh. Do I need to run bitcoind manually?

---- integration::batching::receiver_forwards_payment stdout ----                                                                                   
Error: JsonRpc(Transport(SocketError(Os { code: 35, kind: WouldBlock, message: "Resource temporarily unavailable" }))) 

[nothingmuch]

If I'm in this nix develop shell is this supposed to supply bitcoind for tests by default?

Yes. The inclusion of the bitcoind package on its own should not affect anything, but setting the environment variable should have that effect

Do I need to run bitcoind manually?

No, the BITCOIND_EXE environment variable just overrides the bitcoind crate supplied binary with a nixpkgs one but other than that it's supposed to work the same (i.e. the bitcoind crate is supposed to use that binary with a config supplied by TestServices).

I'm getting this error for every integration test that requires bitcoind when I run ./contrib/test_local.sh.

---- integration::batching::receiver_forwards_payment stdout ----                                                                                   
Error: JsonRpc(Transport(SocketError(Os { code: 35, kind: WouldBlock, message: "Resource temporarily unavailable" }))) 

EWOULDBLOCK is really weird to me, not sure why anything would be using nonblocking IO flags for the JSON RPC stuff...

can you share and RUST_LOG=debug (bitcoind uses env_logger) output, and a also RUST_BACKTRACE=1 for the error if that's a crash, or if not try and localize it to where it arises?

[DanGould]

Here's the requested log with RUST_LOG=debug RUST_BACKTRACE=1 ./contrib/test_local.sh
nix-bitcoind-mac-fail.log

I'm also perplexed by tests failing when I run just the v2 suite in this configuration:

running 5 tests
test integration::v2::test_bad_ohttp_keys ... ok
test integration::v2::v2_to_v1 ... ok
test integration::v2::test_session_expiration ... ok                                                                                                
test integration::v2::v1_to_v2 ... ok
test integration::v2::v2_to_v2 ... FAILED                        
                                                                          
failures:                                                                                                                                           
                                                                                                                                                    
---- integration::v2::v2_to_v2 stdout ----                                                                                                          
Database running on 127.0.0.1:55252                                                                                                                 
Directory server binding to port [::]:54786                         
Directory server binding to port [::]:54790
thread 'integration::v2::v2_to_v2' panicked at payjoin-test-utils/src/lib.rs:150:5:
assertion `left == right` failed: sender doesn't own bitcoin             
  left: 5000000000 SAT                                                    
 right: 505000000000 SAT                                                                                                                            
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace                                                                       
                                                                                                                                                    

failures:      
    integration::v2::v2_to_v2                                             
                                     
test result: FAILED. 4 passed; 1 failed; 0 ignored; 0 measured; 7 filtered out; finished in 26.12s                                                  
                                     
error: test failed, to rerun pass `-p payjoin --test integration`

It may be unrelated but I figured I should note it regardless